The major aim of this project is to examine in detail the problem solving patterns of mentally retarded adolescents and young adults, and to compare their response patterns to those of noretarded children. Additionally, poorly performing retarded individuals will be induced to follow certain response patterns of successful problem solvers in order to explore the possibility that this will improve their performance. The vehicle for these studies will be the Tower of Hanoi problem, and the principal analytic tool will be chronometric analysis. The Tower of Hanoi apparatus is interfaced with a microcomputer which automatically prints out all responses, the latency to the first reponse, and all inter-response times. Based on the hypothesis that relatively long response times represent the subject's planning of a series of moves, and that long pause times bracketing bursts of responses reflect the subject's planning and execution of a subgoal, pause time patterns will be examined and analyzed. Various types of problems that requie the use of differing search levels and subgoals will be given to the subjects in order to measure the presence or absence of subgoal planning and to tease out the particular strategies that are used to solve problems. Relationship of these patterns to individual and group differences in performance will be examined. Poorly performing retarded individuals will be induced to use the pause time patterns of successful problem solvers, and will be given specific subgoals to pursue, in order to determine if this is a valid approach to improving performance. Increased understanding of the sources of retarded persons' problem solving difficulties should lead to improved methods of training the retarded to solve specific types of simple problems.